The present invention relates to a remotely controllable system for positioning a mobile observation and/or intervention system on a patient. It applies, for example, to medical analysis systems, such as endoscopic or echographic systems or to simple invasive devices such as a puncture needle. It will more specifically be described in the context of the use of an echographic probe (remote echography).
Echography is a very advantageous imaging modality, because of its lightness, harmlessness, and its richness in morphological and functional information. Its implementation requires a particular specialization. Several clinical situations would require for the examination to be performed by telemedicine means.
The simplest solution, used in some telemedicine operations, is for a local operator to put himself in vocal and possibly video connection with a distant expert doctor. It could then be devised for the nurse or even for the patient himself to handle an echographic probe and for the distant expert to guide him and draw a diagnosis therefrom. Such resorting to a distant expert is used in several medical situations but applies with difficulty to echography. Indeed, in echography, the performing and interpretation of the examination are intimately connected. Only the operator, who has controlled the way in which the echographic probe has been displaced on the patient's body, has all the information useful for the interpretation. This feature makes remote echography operations difficult. The local operator must already be relatively well trained, and the remote expert must be able to precisely indicate to him the probe displacements to be performed. Now, such displacements imply 6 degrees of freedom (three translations and three rotations). It can be understood that the expression by the remote expert of the displacement orders in vocal form, and even more their execution by the local operator, may be difficult.
To overcome the disadvantages of the above-mentioned simple remote echography, it would be necessary to enable the distant expert to take control of the displacement of the echographic probe, for example, by controlling a probe assembled on a remote-controlled robot. Such systems using robotics are used in medicine and especially in surgery. For this purpose, robotic architectures of master-slave type are typically used, in which a remote operator has a stress feedback system which enables him to displace a virtual object according to n degrees of freedom and in which a slave system placed close to the patient reproduces the master's motions while said master can feel a resistance to its motion.
In the conventional approach, the master and the slave execute exactly the same motions, the slave being linked to a referential with respect to which the patient's position must be located. The mechanical constraints to which the slave is submitted must remain within limits compatible with the possibilities of synthesis of a stress feedback by the master. Besides, the used mechanical architectures use rigid and relatively heavy structures, even when the useful load has a weight smaller than 10 N. It is thus imperative to design high-performance security systems, able to forbid uncontrolled motions of the robot, which would be likely to harm the patient or the medical and surgical team surrounding him.
FIG. 1 shows a very simplified side view of a patient 1 lying on a table 3 for a conventionally remotely controlled echographic examination. An echographic probe 5 is arranged to contact the patient, for example, his abdomen, by an articulated and remote controlled robot arm system 7. Such a system implies a heavy computer architecture to ensure the control and stress feedback. It should be noted that the slave (supporting the echographic probe) contacts the human body, which exerts against it variable and widely unpredictable pressures. This requires, if the system is desired to securely operate, implementing an extremely complex system. Due to all these constraints, the slave is a costly system.
The dilemma thus currently is the following: to use a local operator guided by a distant expert, which appears to be poorly adapted, or to use a robotic system, having a particularly heavy and expensive mechanical structure and associated computer system.
More generally, the above problem, that is, to provide a low-cost secure remotely controlled positioning system, is posed in many other cases falling or not within the medical field. In the medical field, a problem of the same type is posed, for example, for the remote control in orientation and in position of an endoscope or a puncture needle.
Operations performed under endoscopy grow in number. They require introduction of various tools of generally cylindrical shape through the skin. The number of these tools may be such that the operator is disturbed by its assistants which maintain them for him in an adequate position. For this and other reasons, various systems have been developed to bear and position tools penetrating into the human body upon interventions under endoscopy. These systems are “conventional” robots, which are fastened to the operating table or to the ground, and which displace the tools that they support to the coordinates which are communicated thereto by various interfaces with the user, or even, in some cases, by control of the images observed by the endoscope. Such systems remain heavy and require specific adaptation to take into account security problems linked to the use of relatively rigid systems supporting surgical instruments.
The puncture of various organs of the human body is a widely used method to sharpen a diagnosis (sampling of material for microscopic analyses, measurement of various physical, and especially electric characteristics . . . ), or for therapy (physical, mechanical, chemical, electric destruction . . . ). In many cases, the puncture is performed under control of imaging means (radio, echography, scanner, MRI . . . ). It may be advantageous to robotize the positioning of the puncture needle, which opens up the way to the automated implementation of the puncture gesture in several clinical situations, among which, in particular:                a physically limited access to the patient (scanner, MRI . . . ),        the need to perform the gesture rapidly, and        the need to perform the gesture from a distance.Again, existing remotely controlled robotization and positioning systems are too heavy to enable easy generalization of this type of application.        